Lap truing machine



Nov. 24, 1942. R. s. DU KE LAP TRUING MACHINE 3 Sheets-Sheet 1 Filed Aug. 11, 1941 M0,. 5 w. v

1942- v R. s. DUKE 2,3Q3;03 LAP mums momma Filed Aug. 11, 1941 s sneets-sfieet 2 49 b7 Ll,

Nov. 24, 1942. I R. s. DUKE 2,303,030

' LAP TRUING MACHINE I Filed Aug. 11, 1941 a Sheets-Sheet 3 Patented Nov. 24, 1942 UNITED sTATEs rarest OFFICE LAP TRUIN G MACHINE Robert S. Duke, Houston, Tex.

Application August 11, 1941, Serial No. 406,246

8 Claims. (CI. 29-46) This invention relates to a lap truing machine. It is an object of the invention to provide a machine of the character described designed for shaping the operative surface of the lap used in lens grinding and polishing machines.

In the manufacture of lenses a grinder is employed one element of which comprises a lap having a grinding surface which is of the curve of the desired surface of the lens to be ground. The active surface of the lap eventually becomes misshapened from wear.

It is an object of the present invention to provide a truing machine whereby the active, or grinding, surface of the lap may be restored to its original curve or curves.

' It is another object of the invention to provide a machine of the character described having novel means for mounting the mis-shaped lap therein, and which is equipped with an abrasive surface arranged to cooperate with which is capable of required adjustments to restore the active surface of the lap to the original curve or curves, the range of adjustment being such that a worn lap of any original spherical or toric surface may be restored and the lap thus renewed.

A further object of the invention is to provide in a machine of the character described novel means for balancing the adjusting and grinding mechanism about axes of the supporting spindles.

The invention herein described embodies certain improvements over that type of lap retruing machine disclosed in United States Patent No. 2,122,056, issued to this applicant on June 28, 1938.

- With the above and other objects in View the invention has particular relation to certainnovel features of construction, operation and arrangement of parts, an example of which is given in this specification and illustrated in the accompanying drawings, wherein:

Figure 1 shows a side View of the complete machine.

Figure 2 shows a fragmentary vertical sectional view taken at right angles to the View shown in Figure 1.

Figure 3 shows a fragmentary vertical sectional view of another embodiment taken at right angles to the view shown in Figure 1.

Figure 4 shows a fragmentary elevational View partly in section.

Figure 5 shows a fragmentary elevational view showing an adjusting gauge plate employed.

Figure 6 shows a fragmentary elevational. view the lap and through the clamp erably tubular in form and which is supported on the base 2.

Suitably secured to the upper end of the stand there is a clamp 3 which has a. laterally offset upstanding arm 4 preferably formed integrally therewith. This clamp 3 has a horizontal slit 5 extending partly therethrough and above the horizontal slit 5 has the vertical slit 6 thus forming the clamp jaws 1, 1 which are connected by a clamp screw 8.

An upstanding stem 9 has its lower end fitted and extended downwardly into the stem l and is provided, at one side, with a vertical rack l0.

There is a transverse shaft ll extended through a suitable transverse bearing l2 in the clamp 3 and pinned, or otherwise secured on the shaft l I there is a spur gear I3 which is in mesh with a rack I0. One end of the shaft I] is extended and the hand wheel I4 is secured thereon whereby the shaft I I may be turned and the stem 0 thus elevated or lowered. When it is desired to elevate or lower the stem .9, the clamp screw 8 may be turned to release the clamp jaws I, 1, the clamp screw 8 being provided witha handle 15 for that purpose. When the stem 9 has been ad! justed to the required elevation the clamp screw 8 may be tightened up to cause the clamp jaws 1, 1 to securely grip the stem 3 to hold it immovable at the selected point of adjustment,

The upper end of the stem 9 has the deep socket l6 and is provided, at its upper end, with a lateral notch 11. Fitted within the upper end of the socket l6 there is a bushing I 8 whose up per end is formed with an enlarged head l9 which seats against the upper end. of said stem.

The numeral 20 designates a chuck threaded onto which there is an adjusting nut 2| which rests against the upper end of the head l9. Depending from the chuck through the bushing l8 there is the chuck stem 22 whose lower end is provided with an enlarged stop 23. Between this stop and the lower end of the bushing I 8; and surrounding said stem 22' there is a coil spring 24 which holds the adjusting nut 2| yieldingly in engagement with the head IS. A pin 25 extends laterally from the bushing #8 into the notch lland holds the bushing against turning relative to the stem 9.

The upper end of the chuck 26 is upwardly tapered and blank as at 26a to fit into the correspondingly tapered socket 26 of the lap 26a to be ground. The tapering portion of the chuck has a lateral key 21 to fit into the keyway 28 of the shank of the lap whereby the lap is held against turning on the chuck. The chuck is keyed to the bushing I8 and thereby held against turning. The chuck and the lap 26a thereon may be adjusted vertically by turning the adjusting nut 2|.

As illustrated in Figure 2, the operative face of the lap 26a is convex. This will produce a concave face on the lens ground thereon. If it be desired to produce a convex face on the lens it is, of course, necessary that the operative face of the lap be concaved as shown in Figure 3.

In the form illustrated in Figure 3 there is a stem-29 fitted into the socket l6 and this stem has a lateral pin 30 fitting into the notch H to hold said stem 29 against turning.

The upper end of the stem 29 has a head 3| which rests on the upper end of the stem 9 and rotatably mounted within the head 3| there is a file 32, or other abraiding member. The surface of the abrading member 32 has the contour of a spherical segment.

The upper end of the arm 4 has an outwardly turned spindle 33 and mounted to rotate on the spindle there is a yoke 34. Secured to the yoke 34 there is a vertical guide 35. Slidable on said guide and having a dove-tail connection there- With is an anchor block 36.

A screw shaft 31 is mounted to swivel in a vertical bearing in the guide 35 and has a threaded connection with the anchor block 36 whereby said block 36 may be adjusted vertically. The guide 35 carries a gauge 38 whereby the point of adjustment of the anchor block 36 may :be ascertained. The shaft 31 is equipped with a handle 39 whereby it may be turned.

Extended out laterally from the anchor block 36 there is a spindle bracket 40 whose free end carries the outwardly turned spindle 40a and pivotally mounted on this spindle and upstanding therefrom there is a standard 4| on which there is a gauge 42. There is a file holder arm 43 one end of which is formed with a vertical bearing 44, preferably square, in cross-sectional contour and which is vertically slidable on the standard 4|, said standard being, preferably, of cross sectional contour, as shown in Figure '1, to fit snugly through said hearing. A set screw 45 is threaded through the bearing 44 and is engageable with the standard 4| to hold the arm 43 at any selected point of adjustment. The other end of the arm 43 is formed with a vertical bearing 46 to receive the shank 41 of the file holder 48, inset into the lower face of which there is the file or grinder 49. The shank 41 may be held at any selected point of adjustment in the bearing 46 by means of the set screw 50 which is threaded through the bearing 46 and is engageable with said shank. On the upper end of the shank 41 is a grip member 5| for controlling the movement of the file.

Threaded laterally through the anchor block 36 there is a set screw 52 which may be manipulated bythe handle 53 on its outer end and whose inner end is engageable with said anchor block may be point of adjustment on the guide 35.

The gauge 42 is provided for indicating the radlus of. the dioptric curvature of. the operative the guide 35 whereby. held at any selected surface of the lap 26a. Depending from the yoke 34 and turned laterally there is a lug 54 and in alignment with said lug and extending out from the arm 4 there is'a stop 55. Loosely mounted on the spindle 33 and depending therefrom are the counter-balancing arms 56, 51 which are arranged on opposite sides of said lug and stop as shown more accurately in Figures 1 and 4. There are the counter-balancing springs 58, 59. One end of the spring 58 is connected to the arm 56 and its other end is connected to the pin 66 extending outwardly from the arm 4. The ends of the spring 59 are connected to the respective arms 56, 51. i'hese springs 58, 59 counter-balance the weight of the guide 35 and the appendants thereon, that is to say, said weight will be transmitted through the lug 54 to the arm 56 and will be resisted by the counterbalancing springs 58, 59, the arm 51 engaging with the fixed stop 55. Any attempted movement of the weight in the other direction will be transmitted through the lug 54 to the arm 51 and will be resisted by the spring 59, the arm then being held against movement by the fixed stop 55.

Loosely mounted on the spindle 49a and depending therefrom are the counter-balancing arms 6|, 62 which are arranged on opposite sides of the laterally turned fixed stop 63, depending from the bracket 46 and the laterally turned lug 64 depending from the lower end bearing of the upstanding standard 4|. The free ends of these arms 6|, 52 are connected by a counter-balancing spring 65. The standard 4| is held yieldingly in upright position by the counter-balancing spring 65.

It will be noted that the lap 26a has a convex abrading surface formed for grinding the concave side of the lens. For the purpose of grinding the convex side of the lens the lap 26b has.

been provided and which is re-trued by the file 32 as shown in Figure 3.

As illustrated in Figure 3 there is a chuck 20b threaded onto which there is an adjusting nut 2|a. In this embodiment there is a bushing |8a fitted through the bearing 46, which is carried by the arm 3. This bushing is clamped in said bearing by the clamp screw 50 and its lower end is formed into a head the adjusting nut 2|a. The chuck 26b has a stem 22a which extends axially through the.

. bushing |8a and whose upper end carries a stop 23a. Interposed between the stop 23a and the opposing end of the to hold the adjusting nut 2 ayieldingly against the head I911. The outer end of the chuck stem 22a, the stop thereon and the spring 240, are enclosed by a grip member 3|a which is attached to the outer end of the bushing I811.

The lower end of the chuck 20b is downwardly tapered and blank as at 20c tofit into the correspondingly tapered socket 260 of the lap 26!:

ing the adjusting nut 2|a.

When the surface of the lap becomes mis-shapened as a result of use it may be removed from the lens grinding machine and mounted on the chuck as shown in Figures 2 and 4. Before mounting the lap in place, however, the clamp IQd whose lower end abuts bushing Mia, and surrounding; the steam 22a, there is a coil spring 24a which acts;

the gauge 42 to screw 8 may be released and the hand wheel l4 may be turned to move the stem 9 and the chuck carried thereby downwardly and the lap 26a may then be installed in place and the hand wheel l4 turned in the opposite direction t:elev3;te the stem 9, the chuck and the lap 26a, installed on the chuck to the desired elevation and the clamp screw 8 again tightened to hold the stem 9 at the selected elevation. The clamp screw 45' may then be released and the file holder 48, and file carried thereby, may be adjusted with respect to give the desired radius of dioptric curvature, that is, the base curve, and the screw 45 then tightened up to securely fasten the file holder with respect to the standard 4!. Pinned to the arm 43 there is a gauge plate 66 having the gauge finger 61 at one end, to indicate the proper adjustment of the file4r9, and when said adjustment is made the gauge plate should be removed.

The anchor block 36 is now adjusted in accordance with the particular contour desired for the toric surface of the lap.. If said anchor block be adjusted so as to bring the axis about which the standard 4i turns: into a common horizontal plane with the bearing of the yoke 34 and the file 40 operated over the surface of the lap and about said bearings, as axes, a segment of a spherical surface will be produced on the lap. If, however, said anchor block 36 be adjusted so as to bring the axis of the bearing about which the standard 4| turns out of the horizontal plane of the yoke bearing the surface produced by the file '49 on the lap will be varied from a true spherical segment and will approach a cylindrical surface, the variation in the particular form of the toric surface produced depending upon the relative adjustments of the two axes.

The screw 8 is then loosened and the stem 9 is elevated until the surface of the lap to be operated on is in contact with the file and the clamp screw 8 is then tightened up to hold the stem 9 and the lap carried thereby at the selected point of adjustment.

As will be noted from an inspection of Figures 1, 2 and 4, a wide range of adjustments has been provided to the end that any desired curvature of the operative face of the lap 25a may be produced. During the progress of the work the nut 2i may be adjusted from time to time to hold the lap closely to the file. When the lap has been ground to the desired contour it may be removed from the chuck ready for use in the lens grinder or polisher.

The relative positions on the-lap and file, as shown in Figure 3, are the reverse of the positions of these parts illustrated in Figure 2. In making the adjustments for bringing the lap 261) into proper operative relation with the file 32a the gauge plate 43 should be reversed, end for end, on the arm 43. The other end of the plate has a gauge finger 68 projecting therefor and the file 32 may be adjusted upwardly into contact with said finger to properly adjust the file 32 for the required curve and the gauge plate should be then removed.

The balancing springs have been provided for nicely balancing the adjusting and grinding mechanism, hereinabove described, about the axes of the spindles 33 and 49a.

What I claim is:

1. A lap truing machine comprising a stand, a stem vertically adjustable on the stand, a laterally ofiset upstanding arm on the stand, a yoke .to contact the work, and means a standard vertically adjustable relative to the yoke and mounted to pivot on a horizontal axis, means for holding the standard yieldingly in upright position, a work holder on the stem, a file holder vertically adjustable on the standard, a vertically adjustable'file on the file holder adapted to contact the work and means for fixing the file holder at any selected point of adjustmenton the standard.

2. A lap truing machine comprising a stand, a vertically adjustable stem on the stand, a laterally offset upstanding arm on the stand, a yoke mounted topivot on a horizontal axis on the arm, a vertical guide on the yoke, an anchor vertically adjustable on said guide, a horizontal spindle on the anchor, an upright standard mounted to pivot on said spindle, means for yieldingly holding the standard in vertical position, a work holder on the stem, a file holder vertically adjustable on the standard, a vertically adjustable file on the file holder adapted to contact the work, means for fixing the file at a selected point ofadjustmentand means for fixing the file holder at any selected point of adjustment on the standard.

3." "A-lap truing machine comprising a stand, a vertically adjustable stem on the stand, means for adjusting said stem vertically, means for fixing the stem at any selected point of adjustment, a laterally offset upstanding arm on the stand, a vertically adjustable yoke mounted to pivot on a horizontal axis on the arm, a standard supported by the yoke, means for yieldingly holding the standard in upright position, a Work holder on the stem, a file holder vertically adjustable on the standard, a file on the file holder adapted for fixing the file holder at any point of adjustment on the standard.

4. A lap truing machine comprising a stand, a

stem upstanding from the stand, a laterally olfset upstanding arm on the stand, a yoke mounted on the arm to pivot on a horizontal axis, means for holding the yoke yieldingly in a selected position relative to the arm, a vertical standard supported by and vertically adjustable relative to the yoke, means for fixing the standard at a selected point of vertical adjustment, means for holding the standard yieldingly in upright position, a work holder on the stem, a file holder on the standard, a file on the file holder adapted to contact the work and means for fixing the file holder at a selected point of adjustment on the standard.

5. A lap truing machine comprising a stand, a stem upstanding from the stand, a laterally ofiset upstanding arm on the stand, a yoke mounted on the arm to pivot on a horizontal gnounted to pivot on a horizontal axis on the arm,

axis, a standard supported by and vertically adjustable relative to the yoke, a vertically adjustable work holder adapted to receive and support the work to be operated on, a vertically adjustable file holder and a file thereon, one of said holders being located on the stem and the other being located on the standard and means for fixing saidholders at selected points of adjustment on its support withthe file in contact with the Work.

6. A lap truing machine comprising a stand, a stem upstanding from the stand, a laterally offset upstanding arm on the stand, a yoke mounted on the arm to pivot on a horizontal axis, means for holding the yoke yieldingly in a selected position relative to the arm, a vertical standard supported by and vertically adjustable relative to the yoke, means for holding the standard yieldingly in upright position on the yoke, a work holder adjustably mounted on the stem and adapted to receive and support the work to be operated on, a file holder adjustable on the standard and a file thereon, and means for'fixing said holders at selected points of adjustment on its support with the file in contact with the work.

'7. A lap truing machine comprising a stand, a stem thereon, means for adjusting the stem vertically on the stand, means for fixing the stem at any point of adjustment, a laterally ofiset upstanding arm on the stand, a-yoke mounted to pivot on a horizontal axis on said arm, a guide on the yoke, yieldable means for normally holding the guide in upright position, an anchor on the guide, means for fixing the anchor at a selected point of adjustment on the guide, a standard supported by the anchor to pivot on a horizontal axis, yieldable means normally maintaining the standard upright, a work holder adapted to receive and support the work to be operated on, a file holder and a file thereon, one of said holders being located on the stem and the other being located on the standard and means for fixing one of said holders at a selected point of adjustment on its support with the flle in contact with the work.

8. A lap truing machine comprising a stand, a stem on stand, means for adjusting the stem vertically on the stand, means for fixing the stem at a selected point of adjustment, a laterally offset upstanding arm on the stand, a yoke mounted to pivot on a horizontal axis on the arm, a vertical guide on the yoke, yieldable means normally holding the guide in upright position, an anchor vertically adjustable on the guide, means for fixing the anchor at a selected point of adjustment on the guide, a horizontal bracket fixed to the anchor, a vertical standard supported by the bracket and mounted to pivot on a horizontal axis at right angles to the axis of the yoke, yieldable means normally holding the standard upright, a work holder on the stem to receive and support the work to be operated. on, means for adjusting said work holder, a'file hold:- er mounted'on the standard and a file thereon, means for adjusting said file holder to bring the file into contact with the work on said work holder. ROBERT S. DUKE. 

